The present invention relates to wet processing of semiconductor substrates including a rinse of a soft baked polyimide film prior to further photolithography processing.
Polyimides are widely used in the microelectronics industry. Polyimide films are typically utilized in semiconductor devices as insulators, interlevel dielectrics and passivation layers for various types of metallurgy. Polyimides are preferred over inorganic insulators because they typically have a lower dielectric constant, are more amenable to film processing, and include a wide variety of chemistries that can be chosen to meet the functional requirements for different applications.
Conventional flexible chain polyimides include that derived from pyromellitic dianhydride-4,4'-oxydianiline (PMDA-ODA) polymer precursor solution. This solution is formed by the condensation reaction of PMDA and ODA in N-methylpyrrolidone (NMP). Other conventional polyamic acid precursors used in semiconductor fabrication processes are derived from the condensation reaction of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and p-phenylenediamine (PDA) in NMP. The precursors are prepared with NMP as the solvent in a conventional manner.
It is an object of the present invention to provide an improved semiconductor fabrication process which yields better defined patterns and greatly enhances the uniformity and repeatability of the photolithographic process.